The present invention relates to a projection type display device and more particularly to a projection type display device of high fineness suitable for monitoring at a short distance and applicable to, for example, a personal work station.
Recently, personal work stations having a fineness not lower than 1,000 lines.times.1,000 dots, i.e. 1M pixels, have been becoming popular. As a display device for this type of work stations there has heretofore been used a direct viewing type CRT display.
On the other hand, for work stations there has been a demand for a large screen display and the use of a projection type display device may be one means for meeting such demand. An example of a projection type display device is disclosed in U.S. Pat. No. 4,536,056.
In a direct viewing type display device, light is reflected (several percent) by the front and the back of a glass panel, so the contrast is deteriorated, making pictures difficult to see, under the influence of ambient illumination light entering the glass panel.
In the projection type display device described in the specification of the aforementioned U.S. patent, the anti-ambient light contrast characteristic is improved by a black stripe screen technique, but this display device is for monitoring by a number of people from afar, not suitable for monitoring at a short distance.
The reason why such projection type display device is not suitable for monitoring at a short distance is mainly because its vertical directional angle is as narrow as about .+-.6.degree. to .+-.8.degree. and the greater part of emitted light is locally distributed nearly in the normal direction from the screen.
The applicant in the present case possesses the following U.S. patents relating to a projection type television/display screen:
U.S. Pat. No. 4,478,902 PA1 U.S. Pat. No. 4,531,812 PA1 U.S. Pat. No. 4,536,056 PA1 U.S. Pat. No. 4,576,442 PA1 U.S. Pat. No. 4,725,134 PA1 U.S. Pat. No. 4,609,945 PA1 U.S. Pat. No. 4,729,031 PA1 U.S. Ser. No. 715,950 (March 1985) PA1 U.S. Ser. No. 911,070 (September 1986) PA1 U.S. Ser. No. 277,431 (November 1988) PA1 U.S. Pat. No. 4,420,734 PA1 U.S. Pat. No. 4,433,318 PA1 U.S. Ser. No. 948,251 (December 1986)
also possesses and has filed the following U.S. patents and applications using an optical system:
further possesses the following U.S. patents using a deflecting yoke:
and has filed the following application relating to a television itself: